Conventionally, so-called diagnostic radiography is widely used to obtain internal information of patients, in which an image is acquired by using radiation (X-rays), and diagnosis is done. In conventional radiography, a film is set in a cassette together with a pair of intensifying screens (screen). Radiography is executed by using radiation, and the film is developed to obtain a radiographic image. Films used for this have standard sizes. Generally, so-called 14″×17″ films are maximum and are popularly used.
For whole lower extremity radiography or whole spine radiography aiming at measuring a bone, a 14″×17″ film is too small. Instead, a so-called long cassette is used, and radiography is executed by using a long film. However, a long film is difficult to process in development and the like. Alternatively, a plurality of 14″×17″ films partially overlapping each other are set in a long cassette, and radiography is executed. In this case, after radiography, the films are developed one by one, and then, the plurality of films are bonded by tapes or the like to generate a whole image.
In recent years, apparatuses capable of acquiring a radiographic image directly as a digital image have been developed. In such an apparatus, a detector prepared by fixing stimulable phosphor to a sheet-shaped base plate by application or deposition is irradiated with radiation that has passed through an object so that the stimulable phosphor absorbs the radiation. When the stimulable phosphor is then excited by light or thermal energy, it radiates radiation energy accumulated in absorption as fluorescence. This fluorescence is photoelectrically converted to obtain an image signal.
When the above-described full spine radiography is to be executed by using this apparatus, radiography is executed by using a plurality of stimulable phosphor detectors partially overlapping each other. Then, the plurality of partial radiographic image data are synthesized to generate a whole image.
In, e.g., Japanese Patent Laid-Open No. 2000-232976, collateral information is attached to each partial radiographic image to indicate that the image is a part of a continuous radiographic image. By using the collateral information, synthesized image data is obtained from the partial radiographic images.
In the step of generating synthesized image data from a plurality of partial radiographic images, the plurality of partial radiographic images to be synthesized are designated. If wrong partial radiographic images are selected at this time, no correct synthesized image data can be obtained.
For example, a partial radiographic image of a wrong patient may be selected, or a partial radiographic image obtained in the past may be selected even though the patient is correct. In such a case, no correct synthesized image data can be obtained. In addition, wrong synthesized image data may lead to a wrong diagnosis.